Gauges



F. R. BOOSEY June 3, 1958 GAUGES 2 Sheets-Sheet l Filed June 29 .1955

June 3, 1958 R. BOOSEY 2,836,399

GAUGES Filed June 29, 1953 2 Sheets-Sheet 2 2,836,899 Patented 'June 3,1958 GAUGES Frederick Robert Eoosey, Letchworth, England, assignor toThe Sigma Instrument Company Limited, Latchworth, England, a Britishcompany Application June 29, 1953, Serial No. 364,888

Claims priority, application Great Britain July 1, 1952 Claims. (Cl.33-169) This invention relates to gauges and is concerned with themeasuring head of a pneumatic gauge.

According to the present invention there is provided a measuring headfor a pneumatic gauge, said head comprising a measuring anvil and aneedle valve, the needle valve being connected to the measuring anvil sothat measuring movement of the anvil causes movement of the valve, theneedle part of the valve being located in a jet and being shaped so thatwhen the anvil is moved the annular escape area between the needle partand the jet varies directly with the movement of the anvil.

For a better understanding of the invention, and to show how the samemay be carried into effect, reference will now be made to theaccompanying drawings, in which:

Figure 1 is a side elevational view of a measuring head and its support,

Figure 2 is a longitudinal section through the measuring head, with thesupport removed, and

Figure 3 is a perspective view of a detail of the head.

In Figure 1 the measuring head is shown as possessing a body 1 whichcompletely encases the working parts of the head. The head has ameasuring anvil 3 that cooperates with a second measuring anvil 4. Thebody 1 is rigidly attached to a base member 54 and this in turn isclamped to a base plate 50, which is used as the medium for securing themeasuring head to the machine or mechanism to which it is desired toattach the head.

In the example cited, the base plate 50 is attached by means of a fixingscrew 14 to a block 15, this in turn is fixed to a rail 16, which isattached to the body of the machine, as is also a rail 17 which supportsthe bottom or fixed measuring anvil 4.

The plate 50 (Figure 2) is formed with cavities 51 and slots 52 whichpermit machine screws 53 to pass through the plate 50 and secure thebase member 54 thereto. The heads of the machine screws 53 are sunk intothe plate 50 so that the latter shall present an uninterrupted surfacefor secure attachment within the block 15 (see Figure 1). Blade springs55 are securely fixed to the base member 54, and are similarly anchoredto a floating member 56. Cheeks 57 of a U-shaped bracket 57A carried bythe base member 54 have ball races indicated at 58 which carry atransverse shaft 59 extending between the cheeks 57 and supporting alever 60. The U-shaped bracket 57A is shown in Figure 3 and is securedto the member 54 by a screw 61 and pins 62. A block 87A extendinghorizontally from the base member 54 limits clockwise movement of thelever 60.

The free ends of the cheeks 57 are connected by a transverse bar 63carrying an anchorage 64 for one end of a tension spring 66 the otherend of which is hooked upon an arm 67 secured to the floating member 56.The effect of the tension spring 66 is to tend to hold the floatingmember 56 in a lower position. The member 56 has a laterally extendingblock 5 that carries an adjusting screw 6 lockable thereto by a nut 7.The lower end 8 of the screw 6 co-operates with a block 9 extendinglaterally from the base member 54 and serves as an adjustable stop forlimiting downward movement of the floating member 56. The blade springs55 are parallel and are employed in pairs at the top and bottom of thefloating member 56, the blocks 5 and 9 being located between the twoparallel blade springs 55 of the lower pair. The lower end of thefloating member 56 has a block 68 attached to it, such block beingadapted for removable engagement with the anvil 3.

The lever 60 has sapphire platens 69, 70 at the ends thereof. Theknife-edge 71 of a knife element 72 carried by a spring strip 73 that isclamped to the floating member 56 bears on the platen 69. Flexing of thespring strip 73 permits the distance between the lever pivot 59 and thepoint of contact between the knife-edge 71 and the platen 69 to bevaried. A screw 74 is carried by the floating member 56 for adjustingthe position of the knife-edge 71, the strip 73 spring urging the knifeelement 72 against the tip of the screw 74. The screw 74 is passedthrough a tapped hole in a spring strip 75 that is secured to the member56, the strip 75 serving for restraining adjusting movement of the screw74. The body 1 is provided with a removable cover 76 to provide easyaccess to the screw 74 for adjustment purposes.

The lower end 77 of a needle valve 78 bears on the platen 70 carried bythe lever 60. This needle valve 78 is vertically disposed and is carriedby its untapered spindle portion in a body member 79 that is fixed tothe base member 54 by screws 80. A vertical adjusting screw 81 is passedthrough a tapped hole in the body member 79, the tip of the screw 81abutting against the top of the U-shaped bracket 57A. The screw 81serves for adjusting the body member 79 vertically by an amount of theorder of a few thousandths of an inch. The needle valve 78 is urgeddownwardly by a spring 82'. An open-ended air pipe 83 is passed throughthe top of the body 1 and the lower end portion of the pipe 83 issecured in a recess 84 in the body member 79. The recess 84 leads to acircular orifice or jet 85 in which the needle part 86 of the valve 78operates. The needle part 86 of the valve is formed as a paraboloid orhas part of its surface of paraboloid form.

it will now be appreciated that upon upward displacement of the anvil 3from the position shown in Figure 2 the floating member 56 will beupwardly displaced against the action of the tension spring 66 and willcause the knife edge 71 to rise.

The base member 54 together with the body 1 and the floating member '56,are as a whole adjustable in the direction of movement of the floatingmember 56, with respect to the supporting plate 50. This adjustment isachieved by means of a hollow rod '87, one end of which carries acontrol head 88. The rod 87 is a turning fit in the base member 54 andhas an eccentric portion 89 which is a turning fit in the plate 50. Ashaft 90 passes through the hollow of the rod 87 and has at one end acontrol head 91 fitting within the control head 88 of the rod. The shaft90 has a collar 94 thereon, the collar bottoming in a recess 95 formedin the control head 88. At the other end, the shaft 90 has ascrew-threaded portion 92 which receives a nut 93. It will now beunderstood that when the control head 91 is turned to slacken the nut93, the control head 88 may then also be turned to cause the base member54 with associated parts, to be slidingly adjusted relative to itssupporting plate 50. The degree of adjustment obtainable in way will belimited by the degree of eccentricity of the portion '89 with respect tothe rod 87. A suitable clearance is allowed between the floating member56 and the rod 87 toallow the floating member to move without'foulingthe rod. When. the head 88 has been turned to secure a desired positionof adjustment, the head 91 may be tightened whereby the shaft 9! drawsdown onto the supporting plate fiflby virtue ofthe nut 93, andicauses:the, base "plate :54 tob'e immobilised-with respect-to thesupportingpla'te SO. i j 1 V i The upper endlof thegbody Ilis closedby aplate 96 through which J the upper .end of the pipe 83. projects. Thebody 1 has .a'n'aperture97 that is masked by a. grill 93.

The measuring head described above operates'as follows. Air is "fed'tothe upper end of the pipe 83,:via

the pneumaticg-gauge'systeni described in our co-pending patentapplication. No. 353,744; A workpiece to be measured is introduced:between .the fixed anvil 4 and the;measuring;a nvil .3, whereby 'thelatter is caused to move upwardly. Upward :rnovement of the measuring78, which'is spring-urged downwardly, causes the lever 60 to {rot-ate"so that the platen 69 remains in contact with the knife-edge 71, Theextent of movement of the needle valve 78 is proportional to themovement of the measuring anvil 3. Movement of the needle valve 73causes a change in the annularescape area between the needle part 36 andthe jet 8S and hence changes the rate of flow of air through the pipe 83and alters the pressure of the air in thispipe. Airescaping from the jet85 passes from the body 1 by way and the grill 98. 7

Since the needle part 86'is of paraboloid form it will be understoodthat movement of the valve 73 causes a of the aperture'9l V proportionalalteration in the escape area, hence'the exa tent {of movement of thefloat in the glass manometer tube of said pneumatic gauge system variesdirectly with the movementlof the measuring anvil 3.

a 'By adjusting thepositionat which the knife-edge 71 encounters;.the.platen 69, it is possible to vary the degree of mechanicalmagnification of the measuring head. In the --c-onstructional form ofthe measuring head as shown'it is possibleto adjust the position of theknifeedge to give ,a leverratio between knife-edge movement and needlevalve movement of between 2: 1 and;1:l.

, When it is desired to measure a number of dimensions of a work-piecesimultaneously a plurality of the measuring head-s can be employed, eachmeasuring head being usedin conjunction with an associated pneumaticgauge system. The glass tubes of the pneumatic gauge systems are mounted'side-by-side in front of a sheet having two horizontal tolerance linesruled thereon. Although the permitted tolerances of the'dimensions ofthe work-piece to be measured may difier, it is possible by selectingvalves 78 having differently shaped paraboloid portions and/or bysuitably adjusting the lever ratio, to have all the floats between thetwo horizontal lines when the dimensions of the Work-piece are allwithin the permitted tolerance-s.

For example, one needle valve 78 may be designed to operateover a totalmovement of .005 inch and using the 2:1 ratio referred to, the maximumrange for a measuring head using this needle valve will thereforesociated pneumatic gauge system. By virtue of this ar- 1. A measuringhead for pneumatic gauges, said head comprising a displaceable measuringanvil for contacting a Work-piece to be gauged, there being a jet ofcircular section for connection to a source of air, a needle, aparabolic surface portion on said needle and entered in said jet sothatthe annular escape area between said. surface portion and the peripheryof the jet varies linearly with displacemnet of the needle into and outof the jet, and connecting means between the anvil and the needle tomove the needle in direct proportionality to themovement of the anvil.

2. A measuring head'accor'ding'to claim 1, and further comprising aspindle portion on the needle, and a' body member in which the spindleportion'is slidably carried. 3. A measuring head according to claim 2,wherein the connecting means includes a lever pivoted between its ends,said spindle portion contacting one end portion of said lever, a knifeelement connected to move with the measuring anvil and contacting theother end portion of, said lever, and means for adjusting the point ofcontact between said knife element and said lever, in a directiontowards and away from the pivot of the lever, thereby to adjust theratio of movement of the needle to the move ment of the anvil.

4. A measuring headfor a pneumatic gauge, said head comprising adisplaceable'measuring' anvil for contacting avvork-piece tobe gauged, avalvebodyhaving a passageway for connection to asource of air and a jetto which the passageway leads, the. jet being of circular section, aneedle slidably carried in said valve body, a parabolic surface portionon said needle'and entered-in said ljet so that thefannular escapeareabetween said surface portion and the peripheryiof the jet varieslinearly .withdisplacement of theineedleinto'and out'of thejet, a'basememben means securing the valve body to the base mem-lher, an element onwhich the measuring anvil iscarried, parallel flexible spring stripssupporting said element 7 from the base member, and meanstransmitting'motion from the element to the needle, I I

5. A measuring head according'to claim 4, wherein the means transmittingmotion includes a lever pivoted between its ends onto said base member,a first jewelled platen on one end of the lever and a second jewelledplaten on the other'end of the lever, aspindle portionlon said needle,spring means urgingthe spindle portion into,

contact .Wtih the first platen, a knife element carried by.

the first-mentioned element and contacting the second platen at a pointspaced from the pivot of the lever, and

means for adjusting said point towards and'away from a 7 said pivot,whereby the ratio of movement of the needle to the movement of the anvilcan be varied.

References Cited in the-file of this patent UNITEDSTATES PATENTS 699,779N Great Britain Nov. 18, 1953

